Exhaust valve



W. NOBLE EXHAUST VALVE April'29, 193,0.

Filed May e, 1927 Patented Apr; 29, 1930 UNITED STATES i 'WARRENNOBLE,`OF DETROIT, MICHIGAN EXHAUST VALVE Application mea may e, 19a?. lserial No. 189.228.

This invention relates to the exhaust valves of internal combustionengines., and has for its object to provide a greater period for thedispel-sing of heat from an exhaust valve through its seat tosurrounding metal than is ordinarilyv alforded in exhaust valves as theyare usually constructed and operated.

Ordinarily a single exhaust valve is utilized foreach cylinder of anengine and is maintained unseated throughout the entire exhaust period,during which time it is subjected to all of the heating conditionsresulting from the discharge of exhaust gases, both when lirst releasedin a highly compressed lcondition and While being exhausted -bysubsequent piston displacement, which results in the heating of theexhaust valve to a high degree. It is when the valve isagain seated thatthe main dispersing of l this heat takes place through the valve seatand surrounding metal, and it is obvious that the shorter the durationof opening the valve and the longer the subsequent seating thereof thecooler the valve may be maintained.

The' present invention, therefore, has as an object to provide anexhaust valve arrangevment wherein brief opening and extended' seatedconditions are obtained, and more particularly to provide for theseconditions by the use of two exhaust valves for the same cylinder andthe giving to one valve a rapid opening and closing operation during.the early part of the exhaust period, and to the tion, closing at theend of the exhaust period.

Still further the said invention contemplates the utilizing inconnection with the cylinder of an engineof dual exhaust valves, eachadapted to alternatley open for arelatively short time during the earlypart of 'the exhaust period and for a relatively extended time closingwith the end of the exhaust period, I'so that during one exhaust strokeof an engine onefof the valves operates quickly to relieve compressedexhaust gases and then closes on its seat, While the other -valve opensand remains unseated during the entire exhaust period, thel long andshort periods of opening changing alternately from one -valve totheother with each exhaust stroke of the other valve a relatively extendedopen dura' engine whereb in continued operation, both valves aresubjected to the same heating and cooling conditions.

Still further objects or advantages subsid iary or incidental to theaforesaid objects, or resulting 'from the construction or o eration ofthe invention as itmay be carrie into effect, will become apparent asthe said invention is hereinafter further disclosed.

In carrying the said invention into effect, I may adopt the novelconstruction and arrangement of parts hereinafter described, by way ofexample, having reference to the accompanying drawing, Whereinz-` Figure1 is a fragmentary plan of an engine having a dual exhaust valvearrangement embodying the said invention;

Figure 2 is a transverse section of the Same taken on a plane indicatedVby the line 2"-'- in Figure l; and

Figures 3 and 4 are graphs indicating the action of the said valves.

Similar characters of reference indicate similar parts in the severalfigures of the drawing.

1 is a cylinder and 2 the cylinder head of an engine, the said headhaving mounted therein two exhaust valves 3 and 4 common to thecylinder 1. 5 is an inlet valve, the arrangement of which, however, doesnot enter into the present invention and for that reason will not befurther referred to herein. The combined areas of the two exhaust valvesis ample for the purposes of proper exhaust, and thev said valves areshown as being operated by rockers 6 and 7 which, in turn, are operatedfrom a camshaft 8.

The form of the cams on this camshaft varies from the common practice,in that, the cams for operation of each of the two valves varies in formto give a different duration of lift to the two valves whereby oneofthem opens and closes quickly, whereas 'the other remains open until theend of the exhaust period. To this end the cam of the valve 3 isprovided with a lobel 9 having a quick acceleration and short travel,and the cam of the valve 4 is provided with a lobe 10 havinvr an leasier lift and a longer travel exten( ing throughout the full exhaustperiod. Thus,

it returns to its seat before the completion of thevalves 3 and 4 aregiven the .relative`action indicated vb the graph,`Figure 3, wherein thevertical imension is indicative of the valve lift and the lengthindicative of time,` the dotted line 3**.repre'senting the, action ofvthe valve 3 andthe solid line 4a the action of thevalve 4. It will beseen from this graph that `duration of the opening ofthe valve 3v underthe influence of the cam lobe 9 is short compared with the full exhaustperiod lso that crank rotation be used and further lobes 11 and l2provided on the camshaft for operation of the valvesat the requiredperiods. It is also preferred in this case t'o vary the form 'of theselobes so that-the lobe 12 of the valve 4 provides the rapid lift ofshort duration, and

\ the lobe 11 of the valve 3 a lift of extended and long unseatedperiods.

' and the valve which has duration, as indicated', so that the action ofthe valvesunder the inuence of these valves is that shown in the graphof Fi ure 4 from which it will be seen that the va ve 4 opens and closesquickl returning to its seat before the expiration o the exhaust period,and the valve 3 remains open until the end of the exhaust period; thisbeing the reverse of the opration previously described with reference/for substantially simultaneous' opening of to the lobes 9 and 10.

It will be readilyv seen that this arrangement causes the.valves toalternately change tothe samev alternating conditions of short Theresult of this is that during each exhaust period one of the 'valves issubjected to the main hot discharge of gases from the cylinder, while`the i other takes care of the neral scavenging, ist opened remains openfor only a short time and then reseats before the exhaust lperiod iscompleted so that it is given an'extended length of time to dissi-` pateits heat through the `walls of the cylinder head while the other valveis still open, this condition changing alternately from one valve to theother asv heretofore stated As a consequence, although ample opportunityis v'afforded for the escape ofthe compressed ',gases, both valvesbeing.o en during the early part of the exhaust period, each valve is actuallyafforded in actual continued opera- 1 tion a greater durationof seatedtime than is possible with a single valve which is'required to remainopen during the full exhaust period. A

The invention admitsef desirable modifi-,

cations of valve desi due to a more effective coolin thereof as a sultof the action de,- scribe and solves m y of the problems comthe leadingmonly met with in exhaust valve *practice in a very effective manneras/,Will be readily apparent to those skilled in the-art to'which thisinvention appertains.

. This invention may be developedwithin the scope of the followinvclaims without departing from theessentia -features of the saidinvcntion, :andit is desired that the specilicationand drawing be readas being merely illustrative and not in alimiting sense, exceptasnecessitated by the prior art. lVhat I claim is: Y v f l. Incombination with an internal coinbustion engine cylinder, two exhaustvalves1 and timing means for each of said exhaust both of said valvessubstantiall simultaneously and to close one of said va ves immediatlyafter a substantial reduction inpressure a quick lift cam of shortangular4 duration operating one of said valves, and a slow lift cam oflonger angular duration operating theother of said valves, said camsbeing timed said valves. v

4. In combinationwith an internal combustion engine cylinder, twoexhaust valves, valve-lifting means imposing lifting impulse on one ofsaid valves, and a long valve-lifting impulseon the other ofsaid valvesduring an exhaust .period of the enginez both impulses commencingsubstant a alternating in their operation with said first mentionedvalve-lifting'means and imposing:

impulses on said valves reversed as to duration during the engine.

5. In combination with' an internal combustion engine cylinder, twoexhaust valves, a twolobed cam operating oneof said valves,

a short valvethe succeeding exhaust period of .valves, said timingmeans, operating to open ly simultaneously, and valve-lifting means vone of the lobes being of short angular dura- Y tion and the other oflonger angular dura" -t-ion, and a further two-lobed cam operating theother of the said valves, one of the lobes being of short angularduration and the other of longer an ular duration, the leading..face

of the lobe o long duration ofone cam being"v operative substantiallysimultaneously with extended dwell periods, said means being.

adapted to retain one lof said valves on its face of the lobe of shortdura-- LJ v seat durin substantially one half of one exhaust stro e ofthe englne and to retain the other of said valves on its seat duringsubstantially half of the next exhaust stroke.

7. In combination in an internal combustion engine two exhaust valves,timing means to begin the opening of said valves substanl tiallysimultaneously,.said means permitting one of said valves to attain itsmaximum lift prior to the other of said valves.

8. In combination inan internal combustion engine, two exhaust valves,timing means for beginning the opening of said valves substantiallysimultaneously, said ,timing means permitting each valve to alternatelyfirst reach its maximum lift.

9. The combination as set forth in claim 8, the first of said Valves toreach its maximum lift being adapted to recede from said point prior toattainment of said point by the other valve.

`10. The combination as set. forth in claim 8, 'y

said timing means being adapted to permit the closing of the irst valveto reach its maximum point substantially at the time the other v l valvereaches its maximum point of lift.

In testimony whereof I aiix my signature. WARREN NOBLE.

